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Those days I'm in the mood of criticizing the Ballentine's statistical interpretation, also known as the minimal statistical interpretation. Here I will argue that it is, in fact, neither minimal nor statistical.

The main culprit is that Ballentine repeatedly insists that there is no wave function collapse, or state reduction, or whatever one wants to call it. I'm not saying that Ballentine is wrong about that. What I am saying is that an interpretation which insists that there is no collapse is neither minimal nor statistical.

Why is it not minimal? Because a minimal interpretation should be agnostic about any claim that cannot be directly checked by experiments. The Ballentine interpretation is in agreement with experiments, but there are interpretations which claim the existence of collapse, which are in agreement with experiments too. So the truly minimal interpretation would be the purely instrumental interpretation which is agnostic on the existence of collapse. The Ballentine interpretation is not agnostic, hence it's not minimal.

Why is it not statistical? In the purely statistical interpretation, where the wave function is just a probability amplitude and nothing else, the collapse obviously exists. That's because the probability (conditional probability, to be more precise) suddenly changes when new information (about the measurement outcome) arrives. Therefore the state, which is nothing but the probability amplitude, suddenly changes as well, and this sudden change is called collapse (or state reduction). So the interpretation which insists that there is no collapse is not purely statistical.

So what is the Ballentine interpretation really? It's hard to tell. It's some incoherent mixture of pure instrumentalism and implicit additional variables interpretation, in which explicit talk about additional variables is forbidden (because there is no explicit experimental evidence for their existence). I would describe it as what remains when one first starts with a Bohmian interpretation, then integrates out (averages over) all the unknown details of microscopic Bohmian beables, and finally gets confused by trying to completely forget the Bohmian beables.

EDIT: After a long discussion, in the post

https://www.physicsforums.com/threa...r-minimal-nor-statistical.998661/post-6450421

I have concluded that the so-called "minimal" interpretation is in fact the

The main culprit is that Ballentine repeatedly insists that there is no wave function collapse, or state reduction, or whatever one wants to call it. I'm not saying that Ballentine is wrong about that. What I am saying is that an interpretation which insists that there is no collapse is neither minimal nor statistical.

Why is it not minimal? Because a minimal interpretation should be agnostic about any claim that cannot be directly checked by experiments. The Ballentine interpretation is in agreement with experiments, but there are interpretations which claim the existence of collapse, which are in agreement with experiments too. So the truly minimal interpretation would be the purely instrumental interpretation which is agnostic on the existence of collapse. The Ballentine interpretation is not agnostic, hence it's not minimal.

Why is it not statistical? In the purely statistical interpretation, where the wave function is just a probability amplitude and nothing else, the collapse obviously exists. That's because the probability (conditional probability, to be more precise) suddenly changes when new information (about the measurement outcome) arrives. Therefore the state, which is nothing but the probability amplitude, suddenly changes as well, and this sudden change is called collapse (or state reduction). So the interpretation which insists that there is no collapse is not purely statistical.

So what is the Ballentine interpretation really? It's hard to tell. It's some incoherent mixture of pure instrumentalism and implicit additional variables interpretation, in which explicit talk about additional variables is forbidden (because there is no explicit experimental evidence for their existence). I would describe it as what remains when one first starts with a Bohmian interpretation, then integrates out (averages over) all the unknown details of microscopic Bohmian beables, and finally gets confused by trying to completely forget the Bohmian beables.

EDIT: After a long discussion, in the post

https://www.physicsforums.com/threa...r-minimal-nor-statistical.998661/post-6450421

I have concluded that the so-called "minimal" interpretation is in fact the

*maximal*interpretation, or**maximal denial**interpretation to be more precise.
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